Explanation: Newly discovered
minor planet 2001 KX76 is circled in the top panel
above, a recent composite image from the European Southern
Observatory's 2.2 meter telescope at
La Silla, Chile.
Though 2001 KX76 appears here as single point of light in an
unremarkable star field,
its orbit has been accurately measured by
Astrovirtel,
a newly operational "virtual telescope" capable of mining
many years of archival data for previously unrecognized images
of 2001 KX76.
The results show this
minor
planet to be very distant, now orbiting just beyond
Pluto and Charon in the
realm
of the Kuiper Belt.
At its distance, apparent brightness, and assuming a reasonable
surface reflectivity,
2001
KX76 would be 1,200 kilometers or more across -- larger than
the largest main-belt
asteroid, Ceres.
In fact, the illustration in the bottom panel graphically
compares this size estimate to Pluto, Charon, and the largest
previously known
Kuiper Belt objects, indicating the newfound
minor planet
is second only to Pluto in diameter.
Along with other evidence, the comparison suggests
that
Pluto and Charon are closely related to
Kuiper
Belt worlds like 2001 KX76.